The best mechanical control on the market is that one supplied by Panish Controls.
The best electronic engine control on the market - which has been used by Merritt, Rybovich (on the Magaritavich 42), Garlington, Buddy Davis, Ricky Scarborough, Sculley, Cabo... to name a few - is Glendinning Marine's EEC system.
www.glendinningprods.com
"I know I'm biased... just trying to be helpful"... (I'm not sure who said that, but y'all can blame it on me if you have to).
Rgds, John Glendinning